Hair Is Not Recommended for DNA Preservation
Hair is explicitly not a good candidate for future DNA testing according to the American College of Medical Genetics and Genomics (ACMG), and you should pursue alternative specimen collection methods instead. 1
Why Hair Should Be Avoided
The ACMG 2023 guidelines clearly state that hair, vitreous fluid, synovial fluid, and urine are not good candidates for testing because of the low amount of DNA obtained, contamination issues, and other technical limitations. 1 This recommendation applies even when considering long-term storage for future testing.
Key Problems with Hair:
- Extremely low DNA yield - even with the hair root present, the quantity and quality of DNA is poor compared to blood or tissue 2
- High degradation - DNA in fully keratinized hair is extremely degraded, with variable quality even between different hairs from the same individual 2
- Contamination risk - although hair shafts resist external contamination, the processing challenges outweigh this benefit for clinical genetic testing 3
- Laboratory rejection - many genetic testing laboratories will not accept hair samples due to low success rates 1
What You Should Collect Instead
First Priority: Blood Sample
Collect blood in a purple top EDTA tube for DNA preservation. 1, 4 The National Association of Medical Examiners recommends this as the gold standard for every case where genetic testing may be needed later. 1
- Blood samples provide the highest quality and quantity of DNA
- EDTA tubes are specifically designed for long-term DNA preservation
- This is the most widely accepted specimen type by genetic testing laboratories
Second Priority: Buccal Swab or Dried Blood Spot
If blood collection is not feasible, dried blood spots and buccal swabs are additional sources of DNA that are easy to obtain, store, and ship. 1 However, note that the quantity of DNA from these specimens may be less than blood and may not be accepted by all laboratories. 1
Third Priority: Fresh Tissue
If the above options are unavailable, fresh tissue or cultured cells such as fibroblasts may be more successful in yielding results. 1 Fresh tissue requires proper transport with dry ice if previously frozen. 1
Storage Considerations
Long-term storage requires a DNA banking facility, which is typically beyond the services provided by medical examiner offices or clinical laboratories. 1
- Specimens for postmortem testing are typically irreplaceable, requiring special retention protocols 1
- Sample collection information (date, time of collection after death, storage conditions) must be documented for laboratory acceptance 1
- Families should be counseled on the possibility of DNA banking for future analysis when current testing is negative or unavailable 1
Critical Pitfall to Avoid
Do not rely on hair as your only specimen source. While research studies have shown that hair with roots can yield DNA for forensic STR profiling 5 or with whole genome amplification techniques 6, these methods are not validated or accepted for clinical genetic testing in the postmortem setting. The ACMG guidelines are explicit that hair should not be used for clinical genetic testing purposes. 1